The present invention relates to the delivery of medication to the lungs and more particularly, the present invention relates to a delivery system for the application of an aerosolized medication to the lungs or to a specific region within the lungs with improved delivery rates, efficiencies, and control.
Many types of medication can be administered to a patient via the respiratory tract. Medication delivered through the respiratory tract may be carried with a patient's inhalation breath as airborne particles (e.g. an aerosol or nebula) into the lungs where the medication can cross through the thin membrane of the lungs and enter the patient's bloodstream. Delivery of medication via the respiratory tract is preferred in many circumstances because medication delivered this way enters the bloodstream very rapidly. Delivery of medication to the lungs may also be preferred when the medication is used in a treatment of a disease or condition affecting the lungs in order to apply or target the medication as close as physically possible to the diseased area.
Although delivery of medication via the respiratory tract has been used for delivery of medications for many years, there are difficulties associated with such prior systems that have limited their use and application. For example, conventional methods have provided for only limited medication delivery rates, efficiency, and control. Conventional methods for aerosol delivery result in a substantial portion of the medicine failing to be delivered to the lungs, and thereby possibly being wasted, or possibly being delivered to other parts of the body, e.g. the trachea.
Aerosols in general are relatively short-lived and can settle out into larger particles or droplets relatively quickly. Aerosols can also impact each other or other objects, settle out as sediment, diffuse, or coalesce. Aerosol particles can also be subject to hydroscopic growth as they travel. Delivery of medicine as airborne particles requires conversion of the medicine, which may be in liquid form, to an aerosol followed relatively quickly by application of the aerosol to the respiratory tract. One such device that has been utilized for this purpose is an inhaler. Inhalers may atomize a liquid to form an aerosol which a person inhales via the mouth or nose. Inhalers typically provide only limited delivery of medication to the alveoli of the lungs since much of the medication is deposited on the linings of the respiratory tract. It is estimated that as little as 10-15% of an aerosol inhaled in this way reaches the alveoli.
Aerosol delivery of a medication to a patient's respiratory tract also may be performed while the patient is intubated, i.e. when an endotracheal tube is positioned in the patient's trachea to assist in breathing. When an endotracheal tube is positioned in a patient, a proximal end of the endotracheal tube may be connected to a mechanical ventilator and the distal end is located in the trachea. An aerosol may be added to the airflow in the ventilator circuit, conveyed to the endotracheal tube, and carried by the patient's inhalation to the lungs. A significant amount of the aerosolized medication may be deposited inside the endotracheal tube and the delivery rate of the medicine to the lungs is also relatively low and unpredictable.
The low and unpredictable delivery rates of prior aerosol delivery systems have limited the types of medications that are delivered via the respiratory tract. For new medications that are relatively expensive, the amount of wasted medicine may be a significant cost factor in the price of the therapy. Therefore, it would be advantageous to increase the delivery rate or efficiency of a medicine delivered to the lungs.
It may also be advantageous to be able to target medication to a specific bronchus, or specific groups of bronchia, as desired, while avoiding delivery of medication to other portions of the lungs.
Another consideration is that some medications or other agents that can be delivered as aerosols can have adverse side effects. Therefore, it would be advantageous to minimize the overall amount of medication or agent delivered while maintaining the efficacy of the medication by providing the same or a greater amount of the medication to the desired treatment site.
Taking into account these and other considerations, it would be advantageous to improve the delivery rate and efficiency of aerosolized medicines delivery via the respiratory tract.